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Suite containing over 36 carats of Yogo sapphire
Gemmological Characterisation of Sapphires from Yogo Gulch, Montana

A look at the mining and distinguishing characteristics of this naturally vibrant blue sapphire.

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Accurate Reporting of Key Trace Elements in Ruby and Sapphire Using Matrix-Matched Standards

Presents a group of corundum standards developed by GIA to improve the accuracy and efficiency of its laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) instruments.

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Eight HPHT faceted synthetic diamonds from AOTC Group
Near-Colourless HPHT Synthetic Diamonds from AOTC Group

Presents the gemmological and spectroscopic properties of a suite of synthetic diamonds grown by AOTC using high pressure and high temperature.

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Man Sin mining
Hunting for
“Jedi” Spinels in Mogok

Documents a series of visits to Myanmar in search of exceptionally bright pinkish red spinels possessing no dark tones.

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Beryllium Diffusion of Ruby and Sapphire

The heat treatment of corundum involving lattice diffusion of beryllium (Be) at temperatures over 1800°C has become a major issue in the gem trade.

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Rubies and Sapphires from Winza, Central Tanzania

Since late 2007, rubies and sapphires have been mined by hand methods from both eluvial and primary deposits at Winza in central Tanzania.

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Pegmatite Pits in Nigeria
Gem Localities of the 2000s

The past decade saw some impressive discoveries of diamonds and coloured stones.

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A study of the gems in ciborium from Einsiedeln Abbey
A study of the gems in ciborium from Einsiedeln Abbey

The gemstones that adorn a late-16th-century ciborium from Einsiedeln Abbey in Einsiedeln, Switzerland.

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Cultured pearl prepped for analysis
A Look Inside a Remarkably Large Beaded South Sea Cultured Pearl

A study of the nacre and the cavity of a large Pinctada maxima cultured pearl yields a theory on the specimen’s formation.

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Sapphires from Thammannawa, Kataragama Area, Sri Lanka
Sapphires from Thammannawa, Kataragama Area, Sri Lanka

The February 2012 discovery of high-quality blue sapphires at Thammannawa near Kataragama in south-eastern Sri Lanka has intensified gem mining and exploration in the surrounding area and all over the country.

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